Belt driven continuously variable transmission

Abstract

This invention relates to a belt driven continuously variable transmission having a pressure regulating cam mechanism giving a pulley an axial force which corresponds to transmission torque and eliminates torque transmission by friction between a pressure regulating cam and a fixed race. The stationary sheave, whose outer surface is supported, with rotation free at a case, by a bearing and whose inner side encloses the pressure regulating cam mechanism, has a circular hub elongating axially to the back side of the stationary sheave. Therefore, torque from the engine is transmitted to the fixed race of the regulating cam mechanism through an input member, and further transmitted to the stationary sheave through a roller and a movable race of the regulating cam mechanism. Consequently, the stationary sheave is supported at the case by the bearing and the radial load does not work on the pressure regulating cam mechanism. Therefore, the axial force generated by the pressure regulating cam mechanism can be set to correspond to the torque from the engine side without getting any influence from the torque transmission by friction.

We claim: 
     
       1. A belt driven continuously variable transmission including a primary pulley and a secondary pulley both of which being made of two relatively slidable sheaves being supported by shafts, a pressure regulating mechanism giving an axial force according to the transmission torque to at least one of said pulleys, an actuator mechanism to move movable sheaves of both pulleys axially, a belt wound around both pulleys, improvement comprising; said pressure regulating mechanism which is situated right in front of a power transmission path led to a sheave imparting axial force so that said sheave and said pressure regulating mechanism have no radial interconnection of supporting,   said sheave imparting axial force which is directly supported on a case through a bearing.   
     
     
       2. A belt driven continuously variable transmission defined in claim 1, wherein a sheave which axial force is given has a tubular hub section elongated toward axial direction, and outer side of said hub section is supported by a bearing, and said pressure regulating mechanism is situated in inner side of said hub section. 
     
     
       3. A belt driven continuously variable transmission defined in claim 1, wherein said sheave is a stationary sheave of said primary pulley. 
     
     
       4. A belt driven continuously variable transmission defined in claim 1, wherein said pressure regulating mechanism is a pressure regulating cam mechanism which has an wave-shaped end surface and generates axial force by either positive or negative torque transmission. 
     
     
       5. A belt driven continuously variable transmission of defined in claim 1, wherein said belt driven continuously variable transmission which is used for an automatic continuous variable transmission where connecting a secondary shaft of said belt driven continuously variable transmission to a first rotating element of a planetary gear device; connecting a third rotating element of said planetary gear device, through a clutch, to an input shaft transmitting power to a primary shaft of said continuously variable transmission; furthermore connecting a second rotating element of said planetary gear device to an output section; whereby power transmission is conducted exclusively through said belt driven continuously variable transmission under the condition that said planetary gear device works as a reduction mechanism by releasing said clutch and restraining said third rotating element; by engaging said clutch, said planetary gear mechanism works as a split drive mechanism to combine torque transmitted through said belt driven continuously variable transmission and torque transmitted from said input shaft to said third rotating element.